Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
Schedule of Available-for-sale Securities
Total, cost	$ 37,512		$ 37,512		$ 41,605
Gross unrealized gains	10,913		10,913		7,536
Gross unrealized losses	(351)		(351)		(677)
Marketable equity securities, carrying value	41,600		41,600
Total available-for-sale investments, carrying value	48,074		48,074		48,464
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months, fair value	963		963		5,961
Less than 12 months, gross unrealized loss	154		154		627
Greater than 12 months, fair value	7,327		7,327		2,249
Greater than 12 months, gross unrealized loss	197		197		50
Corporate Bonds
Schedule of Available-for-sale Securities
Fixed maturities, cost	6,289		6,289		7,758
Gross unrealized gains	210		210		324
Gross unrealized losses	(31)		(31)		(56)
Fixed maturities, carrying value	6,468		6,468		8,026
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months, fair value					768
Less than 12 months, gross unrealized loss					12
Greater than 12 months, fair value	4,964		4,964		2,204
Greater than 12 months, gross unrealized loss	31		31		44
Marketable Equity Securities
Schedule of Available-for-sale Securities
Marketable equity securities, cost	31,223		31,223		33,847
Gross unrealized gains	10,703		10,703		7,212
Gross unrealized losses	(320)		(320)		(621)
Marketable equity securities, carrying value	41,606		41,606		40,438
Available-for-sale Securities, Continuous Unrealized Loss Position
Less than 12 months, fair value	963		963		5,193
Less than 12 months, gross unrealized loss	154		154		615
Greater than 12 months, fair value	2,363		2,363		45
Greater than 12 months, gross unrealized loss	166		166		6
Impairment losses, available-for-sale securities	$ 162	$ 917	$ 201	$ 917